Gear pump or fluid motor



Feb. 3, 1959 B. H. MOSBACHER 2,871,794

GEAR PUMP 0R FLUID MOTOR 5 Sheets-Sheet 1 Filed June 1. 195a I. AMI/7 4Q. w I a 0,,

F 1 B. H. MOSBACHER 2,871,794

GEAR PUMP OR FLUID MOTOR Filed June 1, 1953 5 Sheets-Sheet 3 hIA l 2/? 230 7 W. M 7W Feb.'3, 1959 B. H. MOSBACHER 2,371,794

' GEAR PUMP 0R FLUID Mo'rbiz Filed June 1. 1953 5 Sheets-Sheet 4 jnz/enfar Feb. 3, 1959 Filed June 1, 1953 B. H.- MOSBACHER GEAR PUMP 0R FLUID MOTOR S Sheets-Sheet 5 United States PatentO GEAR PUMP OR FLUID MOTOR Bruce H. Mosbacher, Rockford, 111., assignor to Roper Industries, Inc., Rockford, Ill., a corporation of Illinois Application June 1, 1953, Serial No. 358,930

12 Claims. (Cl. 103-428) This invention relates to improvements in gear pumps or fluid motors.

It is an object of this invention to provide a novel and improved gear pump or fluid motor.

It is also an object of this invention to provide a novel gear pump or fluid motor in which the gears are mounted for limited endwise movement withinthefiuid displacement chamber of the device and having provision for automatically positioning the meshing gears endwise within the fluid displacement chamber for optimum performance characteristics at any operating pressure.

Another object of this invention is to provide a novel gear pump or fluid motor in which the gears are forced endwise in opposite directions against respective end walls of the fluid displacement chamber in the housing to have just minimum running clearances thereat at any operating pressure, thereby minimizing leakage around the gears and insuring high volumetric efficiency of the device.

Yet another object of this invention is to provide a novel gear pump or fluid motor having provision for pressure loading the gears endwise in opposite directions against respective end Walls of the fluid displacement chamber in the housing to have minimum running clearances thereat.

A further object of this invention is to provide a pressure loaded gear pump or fluid motor having a drive shaft exposed to high fluid pressure and provided with a novel arrangement for insuring that a low pressure seal is sufficient to prevent leakage out of the housing along the drive shaft.

A still further specific object of this invention is to provide a novel pressure loaded gear pump or fluid motor having provision for restraining the gears against tilting within the housing.

Also, it is an additional specific object of the present invention to provide a novel gear pump or fluid motor having axially shiftable pressure loaded bushings engaging respective ends of the gears and sealed with respect to the housing to prevent'leakage from the fluid displacement chamber along the peripheries of the pressure loaded bushings.

In addition, it is an object of this invention to provide a novel gear pump or fluid motor having helical gears arranged to force the respective gears endwise relative to end walls of the housing to either force the gears against the respective end Walls to have minimum running clearances thereat, or to assist a pressure loading arrangement for the same purpose, or, alternatively, to reduce the eflects of pressure loading to a suitable value by exerting end thrusts on the gears which are opposed to the pressure loading .end thrusts.

Other and further objects and advantages of the present invention will be apparentfrom the following description of four embodiments of the invention, which are shown in the accompanying drawings to illustrate the principles of this invention.

In the drawings:

Figure 1 is a longitudinal section through a first form 2,871,794 Patented Feb. 3, 1959 of the gear pump or fluid motor assembly of the present invention;

Figure 1a is an enlarged fragmentary section showing the seal around a pressure bushing in the Fig. 1 device;

Figure 2 is a transverse section through the meshing gears of the Fig. 1 pump or motor, taken along the line 2-2 in Fig. 1;

Figure 3 is a transverse sectional view taken along the line 33 in Fig. -1; v

Figure 4 is a longitudinal sectional view of a second embodiment of the gear pump or motor assembly according to the present invention;

Figure 5 is a longitudinal section through a third embodiment of the gear pump or motor assembly in accordance with the present invention;

Figure 6 is a longitudinal section through a fourth embodiment of the pump or motor of the present invention;

Figure 7 is a transverse section through this device, taken along the line 7-'-7 in Fig. 6;

Figure 8 is a longitudinal section through a fifth embodiment of the present invention;

Figures 9 and 10' are transverse sections through the Fig. 8 device,taken along the lines 9-9 and 10-10, respectively,in Fig. 8;

Figure 11 is an axial section taken along the line 11-11 in Fig. 9; and

Figure 12 is an axial section, similar to Fig. 11, of a modified construction of the Fig. 8 device.

In the .first embodiment of the present invention, referring to Figs. l-3, there is provided a housing having spaced end plates 10 and 11 and a generally oblong, intermediate housing casting 12, which is clamped between the end plates by bolts 13. Rubber gaskets 14 and 15 are clamped between the intermediate member 12 of the housing and the respective inner faces of the end plates 10 and 11 to prevent leakage thereat.

As best seen in Fig. 2, the intermediate housing member 12 is formed with a pair of parallel, intersecting cylindrical bores 16 and 17 at which are located the meshing spur gears 18 and 19, which form the fluid displacement mechanism of the pump or fluid motor.

From Fig. 1 it will be apparent that the bore 16 extends from the end of the middle housing member 12 adjacent the end plate 10 to an internal transverse shoulder 20 formed by the end wall 21 of the middle housing member at the opposite end of gear 18. A reduced diameter bore 22 extends through the end wall 21 of the middle housing member 12 from the shoulder '20 for receiving the journal 18a of gear 18. The gear journal 18b at the opposite end of the gear 18 carries an annular pressure bushing or hearing in the form of a roller 26 having a cylindrical outer periphery. The roller 26 is press fitted onto gear 18 with its inner face abutting against the adjacent end of the gear. The roller is of a diameter equal to the outer diameter of gear 18 and has a close running fit Within bore 16. As shown in Fig. l, the. combined axial length of the toothed portion of gear 18 and roller 26 is less than the length of bore 16, so that the gear and roller assembly is capable of limited displacement lengthwise Within bore 16.

Thehousing bore 17 for the other gear 19 extends from the end of the middle housing member 12adjacent the end plate 11 to an internal transverse shoulder 23 presented by the end wall 24 of the middle housing member at the opposite end of gear 19. A reduced diameter bore 25 extends from the shoulder 23 through the end wall 24 for receiving the gear journal 1% at that end of gear 19. An annular cylindrical hearing or pressure bushing in the form of a roller 27 is press fitted I onto the gear journal 19a at the opposite end of gear 19 and has its. inner face abutting against the adjacent end of gear 19. The roller 27 has an outer diameter the same as the outer diameter of gear 19 and has a close running fit in bore 17. The combined axial length of the toothed portion of gear 19 and the roller 27 is less than the length of the bore 17, as shown in Fig. 1, so that this gear and roller assembly is adapted for limited displacement lengthwise within the bore 17.

Leakage across the periphery of the rollers is prevented by seals, indicated schematically at 46 and 47, respectively, in Fig. 1. Each of these seals may be constructed, as shown in Fig. la, in the form of a plurality of abutting rubber rings 48 received within a groove 49 formed in the respective housing wall. The inner ones of these rings 48 are V-shaped, or chevron shaped, in cross section, with their respective apexes facing toward the adjacent end of the respective gear. Thus, for example, upon leakage of high pressure fiuid along the periphery of roller 26 from chamber 32 to the suction inlet 28, the high pressure fluid would tend to flatten the rings 28 into more snug engagement with the periphery of roller 26 to prevent such leakage, with the sealing action increasing as the pressure in chamber 32 increases. It is to be understood that this seal is only one of several conventional types of seals which might be used for this purpose, and the assembly of Figs. 1-3 is in no way limited to this particular seal arrangement.

Referring to Fig. 2, the middle housing member 12 is provided with a low pressure passage 28 and a high pressure passage 29., located respectively at opposite sides of the meshing gears. When the device is operated as a pump, the low pressure passage 28 serves as the inlet and the high pressure passage 29 serves as the outlet, the reverse holding true for motor operation. A pressure distributing channel 30 is formed in the middle housing member 12 extending from the high pressure passage around the respective peripheries of the gears as far as practicable, while still insuring that the gear teeth provide a seal between the low pressure passage 28 and these high pressure channels. An internal passage 31 in the intermediate housing member 12 extends from the high pressure channel 30 to the chamber 32 in bore 16 at the outer face of roller 26 for applying high pressure against the back of this roller. In like manner, a passage 33 extends from channel 30 to the chamber 34 in bore 17 at the outer face of roller 27 to apply high pressure fluid against the back of this roller.

Gear 19 is formed with an axial bore 35 which effects communication between chamber 34 and the chamber 36 formed in bore 25 between the outer end of the gear journal 19b and the gasket 14 overlying the inner face of the end plate 10.

Gear 18 is formed with an axial bore 37 which is splined for a portion of its extent for the reception of an externally splined drive shaft 38. By leakage along this spline connection between shaft 38 and gear 18, the chamber 32 is in communication with a chamber 39 formed in the reduced bore 22 between the outer end of gear journal 18a and the gasket 15, which overlies the inner face of end plate 11.

As indicated in Fig. 1, the elongated bore 40 in the end wall 15 of the housing defines a relatively long journal bearing for the rotary drive shaft 38. This bore 40 extends between the chamber 39 and a chamber 41 in the housing end plate 11 which is in communication with the low pressure passage 28 through a passage 42 in end plate 11 and a registering passage 43 in the end wall 21 of the intermediate housing member 12. With this arrangement, the close clearance around drive shaft 38 along the long bore 40 provides for a gradual pressure drop from the high pressure chamber 39 to the low pressure chamber 41. This is of considerable advantage because it enables the use of a conventional, inexpensive low pressure seal 44 between rotary shaft 38 and the housing end plate 11 and avoids the necessity of a special high pressure seal at this location. A ball bearing all.

assembly 45 is disposed between the housing end plate 11 and the shaft 38, supporting the shaft for rotation. Snap rings 45a, 45b and 45c locate the ball hearing assembly 45 properly with respect to the housing end plate 11 and shaft 38.

In the operation of this device, assuming pump operation, the shaft 38 is the drive shaft of the pump and is driven by a suitable motive source, such as an electric motor. Drive shaft 38 turns gear 18 counterclockwise in Figs. 2 and 3, and this gear in turn drives the gear 19 clockwise in these views. Thus, the fluid to be pumped is drawn into the low pressure passage 28 and is carried by the intertooth spaces on the gears around to the high pressure passage 29, from which the fluid is discharged from the pump. Through the high pressure channel 30 and passage 31, high pressure fluid is passed from chamber 29 to the chamber 32 to exert pressure against the axially shiftable assembly of gear 18 and roller 26 forcing the gear 18 against the inner face 20 of the opposite end wall 21. In like manner, the assembly of gear 19 and roller 27 is also pressure loaded against the inner face 23 of the end wall 24 of the fluid displacement chamber by means of high pressure fluid supplied to the chamber 34 through channel 30 and pasage 33.

It may be desirable to provide the gear teeth of gears 18 and 19 with a suitable slight helical twist to impart to these gears an initial endwise thrust when the pump is started in order to insure that the gears have a close running fit against the respective housing end walls before the pressure in chambers 32 and 34 has built up.

With the above-described arrangement, there is also high pressure in the chambers 39 and 36 opposing the high presure in chambers 32 and 34 and tending to force the gears away from the respective housing end wall faces 20 and 23. Also, the high pressure fluid acting against the inner faces of the respective rollers 26, 27 and acting against the respective ends of the gears adjacent the housing end wall faces 20 and 23 is distributed by the channel 30 across a major portion of the extent of each gear and roller assembly, as indicated in Fig. 3, tending also to force the gears away from the respective housing end walls. However, due to the greater area of each roller and gear assembly exposed to the high pressure in the respective chambers 32 and 34, there is an unbalance of forces which maintains each gear displaced against the respective housing end wall, with only enough clearance to permit a lubricating film of the pump fluid to provide a running fit thereat.

As already indicated, at the inner side of each gear and roller assembly most of the area of the gear and roller assembly is exposed to the high pressure fluid. However, adjacent the low pressure inlet 28 the inner face of each gear and roller assembly is exposed to low pressure. And since the entire outer side of each gear and roller assembly (at the respective chambers 32 and 34) is exposed to uniform high pressure, this unbalance of forces transversely across the gear and roller. assembly would tend to cause the gear and roller assembly to tilt within the respective housing bore. However, since the gear and roller is in effect an integral unit of relatively long length in the bore, this construction substantially prevents any tilting of the gears due to this factor.

If desired, one might rely upon leakage or slip from the high pressure area in the fluid displacement chamber across the periphery of the rollers 26 and 27 to supply liquid under pressure to the chambers 32, 34 for pressure loading the rollers and gears. if so, the passages 31.. 33 would be eliminated, as would the seals 46, 47. With such an alternative arrangement the pressure in the chamhers 32 and 34 would be somewhat less than that at the high pressure area in the fluid displacement chamber of the pump or motor. However, with the full outer face area or" the rollers exposed to this lesser pressure, the force thereat acting to pressure load the rollers and gears toward the respective shoulders 20, 23 would exceed the. opposing force exerted by the high pressure fluid I which receive the meshing spur gears 58 and 59 forming the rotary fluid displacement mechanism of the pump.

The bore 56 extends from the end of the middle housingmember 52 adjacent end plate 50 to an internal trans verse shoulder 60 formed by the end wall 61 of the middle housing member at the oppositeend of gear 58. A reduced diameter bore 62 extends through the end wall 61 from the shoulder 60 for receiving the gear journal 58a. The gear journal 58b extending from the opposite end of gear 58 is received within a journal bushing 66 having an annular transverse flange 67 which abuts against the end of the toothed portion of gear 58. The bushing 66 is snugly rotatably received within the axial bore 68 formed in a support member 69, which has a cylindrical periphery complementary to the bore 56. The assembly of support 69 and bushing 66 forms a unitary hearing or pressure bushing for the gear 58. The support member 69 is nonrotatably, slidably mounted within the housing bore 56, a key 70 mounted on the intermediate housing 52 being received in a slot 71 formed in the outer periphery of support member 69 for this purpose. The support member 69 is formed with an annular groove 72 in its periphery at which is located an O-ring 73 for preventing leakage between the periphery of support member 69 and the housing bore 56. Outwardly from its bore 68, the support member 69 is formed with an axial passage 74 eflecting communication between the bore 68 and the opposite end of the support member 69.

As indicated in Fig. 4, the combined axial length of the assembly of support member 69, bushing 66 and the toothed portion of gear 58 is somewhat less than the length of the housing bore 56, so that the gear and hearing assembly is adapted for limiteddisplacement lengthwise within the housing bore 56. A compression coil spring 75 acts between the gasket 54 and the support member 69 to bias the assembly of support member 69,

bushing 66 and gear 58 toward the housing end wall 61.

The housing bore 57 extends from the end of the middle housing member adjacent end plate 51 to an internal transverse shoulder 86 formed by the end wall 87 of the middle housing member at the opposite end of gear 59. A reduced diameter bore 88 extends through the end wall 87 from the shoulder 86 for receiving the gear journal 5%. The gear journal 59a extending from the opposite end of gear 59 is received within a journal bushing 76 having an annular transverse flange 77 which abuts against the end of the toothed portion of gear 59. The bushing 76 is snugly rotatably received within the axial bore '78 formed in a support member 79, which has a cylindrical periphery complementary to the bore 57. The combination of support member 79 and journal bushing 76 forms a unitary hearing or pressure bushing for the gear 59. The support member 79 is non-rotatably,

slidably mounted within the housing bore 57, key 80 mounted on the intermediate housing member being received in a slot 81 in the outer periphery of support member 79 for this purpose.- The support member 79 is formed with an annular peripheral groove 82 which receives an O-ring 83 for preventing leakage between the periphery of support member 69 and the housing bore 57. Outwardly from its bore 78, the support member 79 is formed with an axial passage 84 eflecting communication between the bore 78 and the opposite end of support member 69. The combined axial length of-the assembly of support member 79, bushing 76 and the toothed portion of gear 59 is somewhat less than the length of the housing bore 57, so that this assembly is capable of limited movement lengthwise within the housing bore 57. A compression coil spring 85 actsbetween the gasket 55 and the support member 79 to bias the assembly of support member 79, bushing 76 and gear 59 toward the housing end wall 86.

Similar to the first-described embodiment, the Fig. 4 device is provided with a low pressure passage and a high pressure passage (not shown), which are located at opposite sides of the meshing gears 58 and 59. A pressure distributing channel 98 is formed in the middle housing member 52 extending from the high pressure passage around the major portion of the peripheries of the gears, in like manner with the channel 30 in Figs. 1-3. An internal passage 91 in the middle housing member extends from the high pressure channel to the chamber 92 formed at the end of bore 56 at the outer face of support member 69 to apply high fluid pressure thereat. Also, a similar passage 93 in the middle housing member extends from channel to the chamber 94 formed at the end of bore 57 at the outer face of support member 79 for supplying high pressure fluid thereto.

Gear 59 is formed with an axial bore 95 communicating with a chamber 96 formed in bore 88 between gasket 54 and the end of gear journal 5912. Through gear bore 95 and the passage 84in the bearing member 79 the chamber 96 receives high pressure fluid from the chamber 94.

Gear 58 is formed with an axial bore 97 which is splined for a portion of its extent to receive an externally splined drive shaft 98. A chamber 99, which is formed in bore 62 between the outer end of gear journal 58a and the gasket 55, is in communication with the high pressure chamber 92 through the passage 74 in the support member 69 and leakage along the spline connection between gear 58 and drive shaft 98.

The housing end plate 51 is formed with an elongated bore 100, defining the journal bearing for drive shaft 98. A chamber 181 at the outer end of this bore communicates, through end plate passage 102 and a registering passage 183 in the end wall 61 of the middle housing member 52, with the low pressure passage of the pump. A gradual pressure drop takes place along the bore from the high pressure chamber 98 to the low pressure chamber 101, in the same manner as the embodiment of the invention shown in Figs. l3. A ball bearing assembly and alow pressure seal (not shown) are also provided for drive shaft 98, identical with Figs. 1-3.

When the Fig. 4 device is operated as a pump, the shaft 98 is the pump drive shaft, gear 58 is the driving gear, and gear 59 is the driven gear. Initially the springs 75 and 85 bias the respective gears 58 and 59 against the housing end wall faces 60 and 86 when the pump is started. As the pump pressure builds up, high pressure fluid is supplied from channel 38 to the chambers 92, 99, 94 and 96 to pressure load the gears toward the respective housing end walls in the same manner as in Figs. 1-3.

The support members 69 and 79 are, of course, restrained by the keys. 78 and 80 from rotating with the respective gears 58 and 59, but are free to move longitudinally with the gears under the influence of the pressure loading. This non-rotatable arrangement of the'support members 69 and 79 is advantageous in that it enables the provision of the O-ring seals 73 and 83 preventing leakage across the peripheriesv of the bearing members, and the bearing surface speed of the gear is reduced.

In some instances, it may be found expedient to eliminate, or plug, the passages 74 and 84 in the support members 69 and 79, thereby eliminating the supply of high pressure fluid to the chambers 99 and 96 which opposes the pressure loading action in the pump. In such case, of course, .it would be unnecessary to provide thelong bore journal for the drive shaft and the suction connection to the chamber 101, as well as the seal around the drive shaft, could also be eliminated.

In the form of the invention shown in Fig. 5, the housing is substantially identical to that of Fig. 1, having spaced end plates 110, 111, an oblong intermediate housing member 112, and gaskets 114, 115 clamped between the end plates and the intermediate housing member. The intermediate housing member has parallel intersecting cylindrical bores 116, 117 which receive the meshing helical gears 118, 119. The housing bore 116 terminates at a transverse shoulder 129 formed by the end wall 121 of the intermediate housing member 112 and defining the limit of movement of gear 118 axially in bore 115, and the housing bore 117 terminates at a transverse shoulder 123 formed by the end wall 124 of the intermediate housing member and defining the limit of movement of gear 119 axially in the opposite direction in bore 117. A reduced diameter bore 122 formed in the end wall. 121 of the intermediate housing member receives the gear journal 118a of gear 113. A reduced diameter bore 125 formed in the end wall 124 of the intermediate housing member receives the gear journal 1191'; of the gear 119.

The pressure bushings or bearings for the gears are identical to those in the Fig. 1 device. The gear journal 1181) has press fitted thereon a cylindrical roller 126 having an outer diameter equal to the outer diameter of gear 118 and having its inner face abutting against the adjacent end of gear 118, remote from the housing end wall 121. Likewise, a roller 127 is press fitted onto the gear journal 119a, with its inner face abutting against the adjacent end face of gear 119, remote from the housing end Wall 124. Both rollers have close running fits in their respective bores. A seal 146 which may be of the type shown in Fig. la, is located within a groove 14% in the intermediate housing member and in engagement with this cylindrical pressure bushing 126 to prevent leakage thereacross. An identical seal 147 located in housing groove 149 prevents leakage across the pressure bushing 127.

The pressure loading arrangement in Fig. is identical to that of Figs. 1-3, there being provided a high pressure chamber 132 at the back side of roller 126 which receives fluid under pressure through passage 131 from the pressure distributing channel 132. The chamber 134 in bore 117 at the back side of roller 127 receives fluid under pressure through passage 133 from the pressure distributing channel 13%. Gear 118 has an axial bore 137 and a splined connection thereat to the drive shaft 138, which extends out through the long bearing provided by the bore 140 in the end plate 151. A low pressure chamber 141 at the outer end of bore 14% communicates through passages 142, 14-3 with the low pressure side of the pump. Chamber 139, formed in bore 122 at the outer end of gear journal 1180, receives high pressure fluid from chamber 132 by leakage along the splined connection of drive shaft 133 to gear 118. Elongated bore 14% provides a pressure drop from chamber 13-9 along the drive shaft to chamber 141, so that only a conventional low pressure seal (not shown) is required for the drive shaft outwardly of the chamber 141. Gear 119 has an axial bore 135 for passing high pressure fluid from chamher 134 to the chamber 136 formed in bore 125 at the outer end of gear journal 1191:.

As is well understood, the helical configuration of the gear teeth will itself produce opposite end thrusts on the gears when the latter rotate in intermeshing relation with one another. By appropriately selecting the direction of helical twist of the gear teeth, these helical end thrusts on the gears can be selectively chosen to either assist or oppose the end thrusts produced by pressure loading. In Fig. 5, the directions of the gear helices are such that these mechanical end thrusts are in the same direction as the respective pressure loading end thrusts, tending Cir to force the respective gears against the housing end walls 121, 124. However, it is to be understood that if the pressure loading end thrusts on the gears are found to be excessive, the direction of helical twist of the gears may be reversed to cause the mechanical end thrusts resulting from the helical shape of the gears to oppose the pressure loading end thrusts, to thereby reduce the not end thrusts on the gears to more appropriate values. Moreover, in some instances, by proper choice of the gear helix angle and gear size, the mechanical end thrusts on the gears resulting from their helical configuration may be sufficient of themselves to urge the gears to a close running clearance against the respective end Walls 121 and 124- of the housing, so that pressure loading may be dispensed with.

In the final form of the present invention, shown in Figs. 6 and 7, the housing is substantially identical to that of each of Figs. 1 and 5, and consists of spaced end plates 210, 211, an oblong intermediate housing member 212 and gaskets 214, 215 clamped between the end plates and respective ends of the intermediate housing member. The intermediate housing member 212 has parallel intersecting cylindrical bores 216, 217 which receive the meshing gears 218, 219. The housing bore 216 terminates at a transverse shoulder 220 formed by the end wall 221 of the intermediate housing member 212 and defining the limit of movement of gear 218 axially in bore 216. The housing bore 217 terminates at a transverse shoulder 223 formed by the end wall 224 of the intermediate housing member 212 and defining the limit of movement of gear 212 axially in the opposite direction in bore 217. A reduced diameter bore 222 formed in the end wall 221 of the intermediate housing member receives the gear journal 218a of gear 213. A reduced diameter bore 225 formed in the end wall 224 in intermediate housing member receives the gear journal 2191) of the gear 21"). At the end of bore 216 remote from the shoulder 226, there is located an annular ring 256, which is press fitted within bore 216 to be secured fixedly therein. This ring 250 has its outer end face abutting against the gasket 214. A similar ring 251 is press fitted within the bore 217 at the end of that bore remote from the shoulder 223, and with the outer end face of this ring abutting against the gasket 215.

The pressure bushings or bearings for the gears are of stepped or shouldered construction. The pressure bush ing 226 is press fitted onto the gear journal 13.8!) and has its inner, larger cylindrical portion snugly received within the bore 216, with its inner face abutting against the adjacent end of gear 218, remote from the housing shoulder 220. The integral outer extension 226a of the pressure bushing 226 is of reduced cylindrical cross section and is snugly received within the central passage 252 formed in the ring 250. The axial length of the inner, larger portion of the pressure bushing 226 is less than the spacing between the adjacent end of gear 218 and the inner end face of ring 250, so that there is provided a chamber 253 located between the inner end face of ring 250 and the annular shoulder 2261) on the pressure bushing 226 formed at the juncture between its inner cylindrical portion and its reduced diameter extension 2260. This chamber 253 is in communication with the suction inlet passage 228 through a passage 254, so that this shoulder on the pressure bushing is exposed to the low pressure at the inlet 228. At the outer end of the rc duced extension 226a of the pressure bushing, there is provided a chamber 232 which communicates with the high pressure discharge passage 229 through a passage 231, formed in the ring 250 and the intermediate housing section 212, which leads to the pressure distributing channel 23G communicating with the high pressure discharge passage. The ring 25% carries a seal 246 for preventing leakage axially along the periphery of the reduced diameter extension 226a of the pressure bushing 226, while 'the .intermediate housing member 212 similarly carries a seal? 247 for preventing leakage across the periphery of the inner, larger portion of this pressure bushing. Both of these seals may be of the type shown in Fig. la.

With this arrangement, it will be noted that the low pressure area in the chamber 253 opposes the pressure loading eifect of the high pressure fluid in chamber 232. By appropriately selecting the respective areas of the pressure bushing 226 which are exposed respectively to the low pressure in chamber 253 and the high pressure in chamber 232, there may be established a suitable net end thrust on the pressure bushing 226 forcing it and gear 218 to the right in Fig. 6 to position the gear 218 with a minimum'running clearance at shoulder 220.

If desired, the chamber 253 could be made the high pressure chamber and the chamber 232 the low pressure chamber in the pressure loading arrangement for this form of the present invention. In that event, the respective areas of the pressure bushing shoulder 226b and the outer end face of the reduced diameter extension 226a of the pressure bushing would be suitably predetermined so as to produce the requisite pressure loading.

The pressure bushing 227 is press fitted onto the gear journal 219a and has its inner, larger cylindrical portion snugly received within the bore 217, with its inner face abutting against the adjacent end of gear 219, remote from the housing shoulder 223. The integral outer extension 227a of the pressure bushing 227 is of reduced cylindrical cross section and is snugly received within the central passage 256 formed in ring 251. The axial length of the inner, larger portion of the pressure bushing 227 is less than the spacing between the adjacent end of gear 219 and the inner end face of ring 251, so that there is provided a chamber 255 located between the inner end face of ring 250 and the annular shoulder 227b on the pressure bushing 227 formed at the juncture between its inner cylindrical portion and its reduced diameter extension 2270. This chamber 255 is in communication with the suction inlet passage 228 through a passage.

257, so that this shoulder on the pressure bushing is exposed to the low pressure at the inlet 228. At the outer end of the reduced extension 227a of the pressure bushing, there is provided a chamber 234 which communicates with the high discharge passage 229 through a passage 233, formed in the ring 251 and the intermediate housing section 212, which leads to the pressure distributing channel 230 communicating with the high pressure discharge passage. Ring 251 carries a seal 248 for preventing leakage along the periphery of the reduced diameter extension 227a of pressure bushing 227, while the mtermediate housing member 212 carries a similar seal 249 for preventing leakage along the periphery of the mner, larger portion of this pressure bushing.

With this arrangement, the low pressure area at chamber 255, to which the bushing shoulder 227b is exposed, opposes the pressure loading effect of the high pressure fluid in chamber 232 acting against the outer end face of the reduced diameter extension 227a of the pressure bushing. Thus, by appropriately selecting the respective area of the shoulder 227b and the outer end face of the pressure bushing, which are exposed respectively to the low and high pressures, there may be established a suitable net end thrust on the pressure bushing 227 torcing it and gear 219 to the left in Fig. 6 to position the gear 219 with a minimum running clearance at housing shoulder 223.

If desired, the chamber 255 could be made the high pressure chamber and the chamber 234 the low pressure chamber in this pressure loading arrangement. If so, the respective areas of the annular shoulder 227a on the pressure bushing and the outer end face of the reduced diameter extension 227a of the pressure bushing would be suitably preselected to produce the desired pressure loading.

' pressure is applied against its radially inner face.

'10 The gear 218 may havea connection to its drive shaft 238 identical to that discussed in detail in connection with Figs. 1-3. .Likewise, the bearing and seal arrangement for this drive shaft may, if desired, be the same as that for the drive shaft in Figs. 1-3.

In the operation of this device, the rings 250 and 251 'are stationary, while the pressure bushings 226, 227

rotate with the respective gears and the pressure loading against these pressure bushings is effective to force the gears endwise to have close running clearances at the respective housing shoulders 220, 223.

In the fifth embodiment of the invention, referring to Figs. 8-11, the housing comprises spaced end plates 350, 351 and an oblong intermediate housing member 352 clamped between these end plates in fluid-tight relation therewith by means of the resilient gaskets 354, 355.

The intermediate housing member 352 is formed with a pair of intersecting, parallel cylindrical bores 356 and 357 which receive the meshing spur gears 358 and 359, respectively, forming the rotary fluid displacement mechanism' of the pump or fluid motor. At opposite sides of the meshing gears the intermediate housing member is formed with the low pressure passage 328 and the high pressure passage 329, a pressure distributing channel 390 in the intermediate housing member extends from the high pressure passage 329 around the major portion of the peripheries of the gears.

The bore 357 extends from the gasket 354 to an internal transverse shoulder 386 formed by the end wall 387 of the intermediate housing member 352 at the end of'gear 359 remote from the gasket 355. A reduced diameter bore 388 extends through this end wall 387 from the shoulder 386 for receiving the gear journal 359b, which is integral with gear 359.

The gear journal 35% extending from the opposite end of gear 359 is received within a journal bushing 376 having a transverse annular flange 377 which abuts against the end of gear 359 remote from the housing shoulder 386. The bushing 376 is snugly rotatably received within the axial bore 378 formed in the support member 379, which at its inner end has a cylindrical periphery substantially complementary to the bore 357. A peripheral groove 400 is formed on this inner end of the support member 379 and receives a seal in the form of a rubber ring 401, which is channel shaped in cross-section (Fig. 8), so as to be capable of expanding radially outward tightly against the housing bore 357 when fluid The support member 379 is non-rotatably, slidably mounted within the bore 356. A key 380 mounted on the intermediate housing member is received in an elongated slot 381 formed in the periphery of the inner end of support member 379 to prevent the support member from turning, while permitting it to slide axially a limited amount.

At its outer end 402 the support member 379 has a reduced outer periphery which is eccentric to the axis of gear 359, as best seen in Figs. 9 and 10. At the juncture of the larger cylindrical inner end of the support member 379 and its reduced outer end 402 there is formed a transverseshoulder 403 presenting a wall area extending transversely of the axis of bore 357 and eccentric to that axis, to provide a substantially greater wall area at the high pressure side than at the low pressure side of the housing, for a purpose which will become apparent hereinafter. A supporting ring member 404 is press fitted within the bore 357 immediately adjacent gasket 354. This ring member 404 has an eccentric bore which snugly, slidably receives the eccentric reduced outer end 402 of the support member 379.

A. chamber 405 within bore 357 is formed between the inner end of the stationary ring member 404 and the transverse eccentric shoulder 403 on the slidable support member 379. A passage 406 (Fig. 11) drilled through the larger inner end of support member 379 and the transverse flange 377 on bushing 376 effects communicationbetween this chamber 405 and the high pressure side of the fluid displacement chamber at the meshing gears, so that high pressure fluid is applied against shoulder 403 to pressure load the assembly of support member 379, bushing 376 and gear 359 axially to the left in Fig. 8. A transverse passage 487 in the support member 379 eitects communication between high pressure passage 466 and the inner face of the seal 401 at the peripheral groove 400v in the support member 379 for the application of fluid pressure against this seal to urge it tightly against the bore 357.

A passage 411 extends through the transverse bushing flange 377 and the support member 379 from the low pressure side of the fluid displacement chamber at the meshing gears to the chamber 412 at the outer end of support member 379. An axial bore 395 through gear 358 effects communication between this chamber and a chamber 396 formed in passage 388 between the outer end of gear journal 3591; and the gasket 353.

The reduced end 402 of the support member 379 is formed with a groove 498 in its periphery at which is located an O-ring 469 providing a seal between the support member and ring member 404. A coil spring 410 is under compression in chamber 412 between the inner face of gasket 354 and the outer end of the support member 379 to bias the assembly of gear 359, bushing 376 and support member 379 to the left in Fig. 8.

In like manner, at the inner end of the other bore 356 there is provided an internal transverse shoulder 360 formed by the end wall 361 of the intermediate housing member 352. A reduced diameter bore 362 extending through this end wall receives snugly the gear journal 358a.

The gear journal 3581) extending from the opposite end of gear 358 is received within a journal bushing 366 having a transverse annular flange 367 at its inner end which abuts against the end of gear 358 remote from the housing shoulder 360. The bushing 366 is snugly rotatably received within the axial bore 368 formed in the support member 369, which at its inner end has a cylindrical periphery substantially complementary to the bore 356. A peripheral groove 420 on this inner end of the support member 369 receives a seal in the form of an annular rubber ring 421, which is channel shaped in cross-section, so as to be capable of expanding radially outward tightly against the bore 356. The support member 369 is nonrotatably, slidably mounted within bore 356. mounted on the intermediate housing member 352 extends into an elongated slot 371 formed in the periphery of the inner end of support member 369 to prevent the support member from turning, while enabling it to slide axially within bore 356 a limited amount.

At its outer end 422 the support member 369 has a reduced outer periphery which is eccentric to the axis of gear 358, in the same manner as the support member 379, just described. At the juncture of the larger inner end of support member 369 and its reduced outer end 422 there is formed a transverse shoulder 423, which presents a wall area extending transversely of the axis of bore 356 and arranged eccentric to said axis, providing a substantially greater wall area at the high pressure side of the pump or fluid motor than at the low pressure side. A ring member 424 is press fitted within the bore 356 immediately adjacent gasket 353 and has an eccentric inner periphery which snugly, slidably receives the eccentric reduced outer end of the support member 369.

A chamber 425 within bore 356 is formed between the inner end of the stationary ring member 424 and the transverse eccentric shoulder 423 on the slidable support member 369. ln like manner with the passage arrangement in the above-described support member 379 for the other gear, the support member 369 is formed with a passage (not shown) leading from the high pressure side of the gears to the chamber 425, as well as an intersecting-pas A key 370 sage (also not shown) leading to the groove 420 beneath the seal 421. Thus, high pressure fluid is supplied to the chamber 425 and to the underside of the seal 421, so that the assembly of gear 353, bushing 366 and support member 369 is urged axially to the right in Fig. 8 and the seal 421 is forced radially outward tightly against the bore 356. Also, a passage (not shown) extends through the support member 369 from the low pressure side of the gems to the chamber 432 in stationary ring 424 formed between the inner face of gasket 353 and the outer end of support member 369. An axial bore 397 extends through gear 358' and effects communication between this chamber 432 and the chamber 399 formed in bore 362 between gasket 354 and the outer end of the gear journal 358a.

At the chamber 432 there is located a coil spring 430, which is under compression between the inner face of gasket 353 and the outer end of the support member 369 and which biases the assembly of gear 358, bushing 366 and support member 369 axially to the right in Fig. 8. A peripheral groove 428' on the reduced outer end 422 of the support member 369 receives an O-ring 429, which provides a seal thereat between the support member 369 and the stationary ring 424 which supports it.

With the above-described arrangement, tilting of the gears is minimized because of the relatively small wall areas at the shoulders 403 and 423 on the support members 379 and 369, respectively exposed to high pressure at the low pressure side of the pump or fluid motor. Thus, the fluid force unbalance between the opposite ends of the bearing assembly at the low pressure side of the pump is greatly reduced by this construction of the support members 379 and 369.

In the Fig. 12- modification, the arrangement is basically similar to the above-described mechanism of Figs. 8-11, except that the pressure connections are reversed and the slidable, non-rotatable support member has a closed outer end.

Referring to Fig. 12, the gear 359' is rotatably received within the bore 357 formed in the intermediate housing member 352' of the pump or fluid motor. An end wall 387' of this intermediate housing member defines a shoulder 386 extending transversely across bore 357. A reduced diameter passage 383' extends through this end wall and receives snugly a bearing bushing 448, which has an annular transverse flange 441 at its inner endabutting against one end of gear 359. This bushing 440 receives snugly and supports rotatably the gear journal 35912.

The gear journal 359a extending from the opposite end of gear359' is snugly, rotatably received within an axial recess 387' in the support member 379'. At its inner end the support member 379 presents an axial face abutting against the adjacent end of gear 359' and has a cylindrical periphery snugly received within the housing bore 357. A peripheral groove 480' on this inner end of support member 379 receives a seal in the form of an annular rubber member 401 having a channel shaped cross-section. This annular member expands radially outward tightly against the bore 357 when fluid pressure is applied against its underside. As in the above-described embodiment of Figs. 8-11, the support member 379' is non-rotatably, slidably supported within bore 357 for limited axial movement.

At its outer end 402' the support member 379' has a reduced outer periphery which is eccentric to the central axis of housing bore 357'. At the juncture of the inner and outer ends of the support member 379 there is formed a transverse shoulder 403' presenting a wall area eccentric to the axis of housing bore 357', with a much greater wall area at the low pressure side of the pump or fluid motor. A ring member 404' press fitted within bore 357' immediately adjacent the gasket 354' has an eccentric bore which snugly, slidably receives the eccentric reduced outer end 402' of the support member 379'.

A-chamber 405 within bore 357' is formed between the transverse shoulder 403' on the support member 379' and the axially inner face of ring 404'. A passage 411' drilled through the inner end of support member 379 effects communication between this chamber 405f and the low pressure side of the gears.

The support member 379 is formed with an end wall 379a which closes the outer end of this support member. This outer end wall is exposed to a chamber 412 formed in the eccentric passage in ring 404 between this end wall and the gasket 354. As Will be obvious, this outer end wall 379a on the support member 379' extends eccentric to the axis of housing bore 357', with a much greater wall area at the high pressure side of the pump or fluid motor than at the low pressure side thereof. A passage 496' extends through the support member 379' from the high pressure side of the gears to the chamber 412' for supplying fluid at high pressure to this chamber to urge the assembly of gear 359 and support member 379' toward the housing shoulder 386'. An intersecting passage 407 is provided for supplying high pressure fluid to the underside of seal 401 to force the latter radially outward against the bore 357 A compression coil spring 410 located in chamber 412' biases the support member 379' and gear 359' in a direction toward the housing end wall 386'. A peripheral groove 408' on the reduced outer end 402 of the support member 379' carries an O-ring 409', providing a seal along the support member between the chambers 405' and 412'.

In this modification, when fluid under high pressure is supplied to chamber 412 the fluid force unbalance on opposite ends of the support member 379' at the low pressure side of the pump is minimized because of the small area of end wall 379a at the low pressure side. In this manner, any tendency for the support member 379' to tilt is materially reduced.

While in the foregoing description and the accompanying drawings there have been disclosed several preferred embodiments of the present invention, it is to be understood that various modifications, omissions and refinements which depart from the disclosed embodiments of the invention may be adopted without departing from the spirit and scope of the present invention.

.1 claim:

1. A gear pump or fluid motor comprising a housing defining a pair of parallel intersecting cylindrical bores, a pair of meshing rotary gears in said bores, a low pressure passage and a high pressure passage communicating with said bores on opposite sides of said meshing gears, axially movable pressure bushings in said bores having their front faces next to respective ends of the gears, means for applying high fluid pressure against the respective back faces of said pressure bushings, a rotary drive shaft separate from said gears and drivingly connected to one of said gears and exposed to the high pressure fluid at the back face of the respective pressure bushing, said drive shaft extending out through said housing, said housing having a bearing for said drive shaft which is long as compared to the diameter of said shaft and extends in a direction away from said gear, said housing defining a chamber at the outer end of said long bearing communicating with said low pressure passage to establish a pressure drop along the drive shaft toward said chamber, and a low pressure seal acting between said housing and said drive shaft outwardly from said chamber to prevent leakage of fluid along the drive shaft out of the housing.

v2. A gear pump or fluid motor comprising a housing defining a pair of parallel intersecting cylindrical bores, a pair of meshing rotary gears in said bores, a low pressure passage and a high pressure passage communicating with said bores on opposite sides of said meshing gears, axially movable pressure bushings in said bores having their inner faces next to respective ends of the gears,

means. for; applying fluid pressure against the respective outer facesof said pressure bushings, one of said gears and exposed thereat to the fluid pressure in said axial passage, said'drive shaft extending from said connection out through said housing, said housing having a bearing for said drive shaft which is long as compared to the diameter of said shaft and extends in a direction away from said gear, said housing defining a chamber at the outer end of said long bearing communicating with said low pressure passage to establish a pressure drop along the drive shaft toward said chamber, and a low pressure seal acting between said housing and said shaft outwardly from said chamber to prevent leakage of fluid along the shaft out of the housing. 1

3.- A gear pump or fluid motor comprising a housing having a pair of parallel intersecting bores, first and second meshing gears in said bores, said housing including a first end wall extending transversely across one bore and limiting the movement of the first gear axially in one direction in said bore, said housing including a second end wall. extending transversely across the other of said bores and defining the limit of movement therein of the second gear axially in the opposite direction, a first bearing memberhaving an outer diameter equal to the outer diameter of the first gear and snugly, slidably received in said one bore at the end of the first gear remote from said end wall and attached rigidly to said first gear to rotate therewith and support said gear for axial movement in said one bore, a second bearing membet" having an outer diameter equal to the outer diameter of the second gear and snugly, slidably received in said other bore at the end of the second gear remote from said second end wall and attached rigidly to said second gear to rotate therewith and support said second gear for limited axial movement in said other bore, and means operative while the gears rotate for exerting opposite axial'thrusts on the gears forcing the gears in opposite axial directions against the respective end walls to have minimum running clearances thereat.

\ 4. A gear pump .or fluid motor comprising a housing having a pair of parallel intersecting cylindrical bores, first and second rotary meshing gears in said bores, said housing including a first end wall extending transversely across one of said bores and defining the limit of endwise movement of the first gear in one direction in said bore, said housing including a second end wall extending transversely across the other of said bores and defining the limit of movement therein of the second gear endwise in the opposite direction, a first bearing having a cylindrical outer periphery equal in diameter to the outer diameter of the first gear and snugly, slidably received infsaid one bore, said first bearing abutting against the end of said first gear remote from said first end wall and rigidly attached to said first gear to rotate therewith'and to support said first gear for limited endwise movement in said one bore, a second bearing having a cylindrical outer periphery equal in diameter to the outer diameter of the second gear and snugly, slidably received in said other bore, said second bearing abutting against the end of the second gear remote from said second end wall and rigidly attached to said second gear to rotate therewith and to support said second gear for limited endwise movement in said other bore, and means operative while the gears rotate for exerting endwise thrusts on the gears forcing them in opposite axial-directions against the respective end walls to have minimum running clearances thereat. v

5. A gear pump or fluid motor comprising a housing having a pair of parallel intersecting cylindrical bores,

15 iii-stand second rotary meshing gears in said bores, said housing including a first end wall extendin transversely across one of said bores and defining the limit of endwise movement of the first gear in one direction in said bore, said housing including a second end wall extending transversely across the other of said bores and defining tlte limit of movement therein of the second gear endwise in the opposite direction, a first bearing having a cylindrical outer periphery equal in diameter to the outer diameter of the first gear and snugly, slidably received in said one bore, said first bearing abutting at its inner face against the end of said first gear remote-from said first end wall and rigidly attached to said first gear to rotate therewith and to support said first gear for limited endwise movement in said one bore, a second bearing having a cylindrical outer periphery equal in diameter to the outer diameter of the second gear and snugly, slid ably received in said other bore, said second bearing abutting at its inner face against the end of the second gear remote from said second end wall and rigidly attached to said second gear to rotate therewith and to support said second gear for limited endwise movement in said other bore, and means for applying fluid pressure against the outer faces of said bearings to urge the respective gears in opposite directions endwise against the respective end walls to have minimum running clearances thereat.

6. A gear pump or fluid motor comprising a housing having a pair of parallel intersecting cylindrical bores, first and second rotary meshing gears in said bores, said housing including a first end wall extending transversely across one of said bores and defining the limit of endwise movement of the first gear in one direction in said bore, said housing including a second end wall extending transversely across the other of said bores and defining the limit of movement therein of the second gear endwise in the opposite direction, a first bearing having a cylindrical outer periphery equal in diameter to the outer diameter of the first gear and snugly, slidably received in said one bore, said first bearing abutting against the end of said first gear remote from said first end Wall and rigidly attached to said first gear to rotate therewith and to support said first gear for limited endwise movement in said one bore, said first gear being of substantial length in said one bore and coacting with said first bearing to restrain the latter against tilting in said one bore, a second bearing having a cylindrical outer periphery equal in diameter to the outer diameter of the second gear and snugly, slidably received in said other bore, said second bearing abutting against the end of the second gear remote from said second end wall and rigidly attached to said second gear to rotate therewith and to support said second gear for limited endwise movement in said other bore, said second gear being of substantial length in said other bore and coacting with said second bearing to restrain the latter against tilting in said other bore, and means operative during rotation of the gears for exerting endwise thrusts on the gears forcing them in opposite axial direction against the respective and walls to have minimum running clearances thereat.

7. A gear pump or fluid motor comprising a housing having a pair of parallel intersecting cylindrical bores, first and second rotary meshing gears in said bores, said housing including a first end wall extending transversely across one of said bores and defining the limit of endwise movement of the first gear in one direction in said bore, said housing including a second end wall extending transversely across the other of said bores and defining the limit of movement therein of the second gear endwise in the opposite direction, a first bearing having a cylindrical outer periphery equal in diameter to the outer diameter of the first gear and snugly, slidably received in said one bore, said first bearing abutting at its inner face against the end of said first gear remote from said first end wall and rigidly attached to said first gear to rotate therewith and to support said first gear for limited endwise movement in said one bore, said first gear being of substantial lengtn in said one bore and coacting with said first bearing to restrain the latter against tilting in said one bore, a second bearing having a cylindrical outer periphery equal in diameter to the outer diameter of the second gear and snugly, slidably received in said other bore, said second bearing abutting at its inner face against the end of the second gear remote from said second end wall and rigidly attached to said second gear to rotate therewith and to support said second gear for limited endwise movement in said other bore, said second gear being of substantial length in said other bore and coacting with said second hearing to restrain the latter against tilting in said other bore, and means for applying fluid pressure against the outer faces of said bearings to urge the respective gears in opposite axial directions against the respective end walls to have minimum running clearances thereat.

87 A gear pump or fluid motor comprising a housing having a pair of parallel intersecting cylindrical bores, first and second rotary meshing gears in said bores, a low pressure passage and a high pressure passage communicating with said bores on opposite sides of said meshing gears, said housing including a first end wall extending transversely across one of said bores and defining the limit of endwise movement of the first gear in one direction in said bore, said housing including a secend end wall extending transversely across the other of said bores and defining the limit of movement therein of the second gear endwise in the opposite direction; a first pressure bushing having a cylindrical outer periphery equal in diameter to the outer diameter of the first gear and snugly, slidably received in said one bore, said first pressure bushing abutting at its inner face against the end of said first gear remote from said first end wall and rigidly attached to said first gear to rotate therewith and to support said first gear for limited endwise movement in said one bore, a second pressure bushing having a cylindrical outer periphery equal in diameter to the outer diameter of the second gear and snugly, slidably received in said other bore, said second pressure bushing abutting at its inner face against the end of the second gear remote from said second end wall and rigidly attached to said second gear to rotate therewith and to support said second gear for limited endwise movement in said other bore, means for applying fluid pressure against the respective outer faces of said pressure bushings, a rotary drive shaft separate from said gears and drivingly connected to one of said gears and exposed to the high pressure fluid at the outer face of the respective pressure bushing, said drive shaft extending out through said housing, said housing having a bearing for said drive shaft which is long as compared to the diameter of said shaft extending in a direction away from said gear, said housing defining a chamber at the outer end of said long bearing communicating with the low pressure passage to establish a pressure drop along the drive shaft toward said chamber, and a low pressure seal acting between said housing and said drive shaft outwardly from said chamber to prevent leakage of fluid along the drive shaft out of the housing.

9. A gear pump or fluid motor comprising a housing having a pair of parallel intersecting cylindrical bores, first and second rotaiy meshing gears in said bores, said housing having a low pressure passage and a high pressure passage communicating with said bores on opposite sides of said meshing gears, said housing including a first end Wall extending transversely across one of said bores and defining the limit of endwise movement of the first gear in one direction in said bore, said housing including a second end wall extending transversely across the other of said bores and defining the limit of movement therein of the second gear endwise in the opposite direction, a first pressure bushing having a cylindrical outer periphery equal in diameter to the outer diameter of the first gear and snugly, slidably received in said one bore, said first pressure bushing abutting at its inner face against the end of said first gear remote from said first end wall and rigidly attached to said first gear to rotate therewith and to support said first gear for limited endwise movement in said one bore, said first pressure bushing being of substantial length in said one bore and coacting with said first gear to restrain the latter against tilting in said one bore, a second pressure bushing ha ing a, cylindrical outer periphery equal in diameter to the outer diameter of the second gear and snugly, slidably received in said other bore, said second pressure bushing abutting at its inner face against the end of the second gear remote from said second end wall and rigidly at tached to said second gear to rotate therewith and to support said second gear for limited endwise movement in said other bore, said second pressure bushing being of substantial length in said other bore and coacting with said second gear to restrain the latter against tilting in said other bore, means for applying high fluid pressure against the respective outer faces of said pressure bushings to force the respective gears in opposite directions endwise against the respective end walls to have minimum running clearances thereat, and a channel in said housing communicating with said high pressure passage and extending around the peripheries of said gears toward said loW pressure passage to distribute high pressure across the inner faces of said pressure bushings.

10. A gear pump or fluid motor comprising a housing having a pair of parallel intersecting cylindrical bores, first and second rotary meshing gears in said bores, said housing including a first end Wall extending transversely across one of said bores and defining the limit of endwise movement of the first gear in one direction in said bore, said housing including a second end wall extending transversely across the other of said bores and defining the limit of movement therein of the second gear endwise in the opposite direction, a first bearing having a cylindrical outer periphery equal in diameter to the outer diameter of the first gear and snugly, slidably received in said one bore, said first bearing abutting against the end of said first gear remote from said first end wall and rigidly attached to said first gear to rotate therewith and to support said first gear for limited endwise movement in said one bore, a second hearing having a cylindrical outer periphery equal in diameter to the outer diameter of the second gear and snugly, slidably received in said other bore, said second bearing abutting against the end of the second gear remote from said second end wall and rigidly attached to said second gear to rotate therewith and to support said second gear for limited endwise movement in said other bore, and said gears being formed with helical teeth producing endwise thrusts on the gears when the gears rotate forcing the gears in opposite axial directions against the respective end walls to have minimum running clearances thereat.

11. A gear pump or fluid motor comprising a housing having a pair of parallel intersecting cylindrical bores, first and second rotary meshing gears in said bores, said I housing including a first end wall extending transversely across one of said bores and defining the limit of endwise movement of the first gear in one direction in said bore, said housing including a second end wall extending transversely across the other of said bores and defining the limit of movement therein of the second gear endwise in the opposite direction, a first bearing having a cylindrical outer periphery equal in diameter to the outer diameter of the first gear and snugly, slidably received in said one bore, said first bearing abutting against the end of said first gear remote from said first end Wall and rigidly attached to said first gear to rotate therewith and to support said first gear for limited endwise movement in said one bore, a second bearing having a cylindrical outer periphery equal in diameter to the outer diameter of the second gear and snugly, slidably received in said other bore, said second bearing abutting against the end of the second gear remote from said second end wall and rigidly attached to said second gear to rotate therewith and to support said second gear for limited endwise movement in said other bore, said gears being formed with helical teeth producing endwise thrusts on the gears when the gears rotate forcing the gears in opposite axial directions in their respective bores, and means for applying fluid pressure against the outer faces of said bearings to urge the respective gears in opposite directions in their respective bores endwise against the respective end walls to have minimum running clearances thereat.

12. A gear pump or fluid motor comprising a housing having a pair of parallel intersecting cylindrical bores, first and second rotary meshing gears in said bores, said housing including a first end wall extending transversely across one of said bores and defining the limit of endwise movement of the first gear in one direction in said bore, said housing including a second end wall extending transversely across the other of said bores and defining the limit of movement therein of the second gear endwise in the opposite direction, a first bearing having a cylindrical outer periphery equal in diameter to the outer diameter of the first gear and snugly, slidably received in said one bore, said first bearing abutting at its inner face against the end of said first gear remote from said first end Wall and rigidly attached to said first gear to rotate therewith and to support said first gear for limited endwise movement in said one bore, said first gear being of substantial length in said one bore and coacting'with said first bearing to restrain the latter against tilting in said one bore, a second bearing having a cylindrical outer periphery equal in diameter to the outer diameter of the second gear and snugly, slidably received in said other bore, said second bearing abutting at its inner face against the end of the second gear remote from said second end Wall and rigidly attached to said second gear to rotate therewith and to support said second gear for limited endwise movement in said other bore, said second gear being of substantial length in said other bore and coacting with said second bearing to restrain the latter against tilting in said other bore, said gears being formed with helical teeth producing endwise thrusts on the gear when the gears rotate forcing the gears in opposite axial directions in their respective bores, and means for applying fluid pres sure against the outer faces of said hearings to urge the respective gears in opposite directions in their respective bores endwise against the respective end Walls to have minimum running clearances thereat.

References Cited in the file of this patent UNITED STATES PATENTS 344,445 Harrold June 29, 1886 367,374 Deming Aug. 2, 1887 1,285,819 Smith Nov. 26, 1918 2,236,980 Ungar Apr. 1, 1941 2,319,374 Ungar May 18, 1943 2,405,061 Shaw July 30, 1946 2,420,622 Roth et al. May 13, 1947 2,527,941 Lauck et a1 Oct. 31, 1950 2,580,006 Densham Dec. 25, 1951 2,624,287 Ilyin Jan. 6, 1953 2,649,740 Murray et al Aug. 25, 1953 2,676,548 Lauck Apr. 27, 1954 2,682,836 Orr July 6, 1954 2,695,566 Compton Nov. 30, 1954 2,699,724 Murray et al Jan. 18, 1955 2,714,856 Kane Aug. 9, 1955 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION:

Patent No 2,8'7l 794 I Bruce Mosbacher February 3, 1959 It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction and'that the said'Let'bers Patent should read as corrected below.

Column 15, line 58, for "and Walls" read end Walls Signed and sealed this 26th day of May 1959.

(SEAL) Attest:

KARL Ho AXLINE Attesting Oflicer ROBERT C. WATSON Commissioner of Patents 

